Trenches or ditches are commonly excavated so that pipe, cable, or other materials can be installed underground. When digging trenches and working within trenches, a difficulty arises with respect to supporting the sidewalls of the trench so that debris and other loose material does not fall into a working area of the trench. There are also problems with respect to safety of workers within the trench where falling material may strike the persons working within the trench.
Stationary trench boxes have traditionally been used within trenches to provide a working area for workers. The trench boxes are typically employed after a backhoe or other excavating device digs the trench. The primary purposes of the trench boxes include preventing loose or broken material from falling into the working area of the trench and injuring workers within the trench, and to simply maintain the working area free of such loose or broken material. Traditional trench boxes do not perform excavating functions, since their primary purpose is to provide a partitioned working area.
A traditional trench box comprises two sidewalls and interconnecting structural members. It is generally desirable to leave as much space as possible within the two side panels to allow the workers to move about within the trench box while laying pipe, cable, or performing repair work.
Traditional trench boxes have traditionally been moved by a crane or another lifting mechanism by lowering the trench box into the trench. Once in the trench, they have traditionally been moved back and forth in the trench by a backhoe that has dug the trench or another separate piece of machinery. In the case of the backhoe, it is required to perform a double duty: dig the trench and move the trench box back and forth within the trench. This, of course, slows down the efficiency and speed of work that can be performed within the trench.
Because of the traditional bulkiness of equipment needed to move a large piece of equipment such as a trench box, a means for propelling a trench box has not been suitably provided in prior trench boxes because of the amount of space the drive means would require within the trench box.
Some prior self-propelled excavating equipment have included various types of trench-shoring structures. However, such excavating devices cannot be suitably employed as trench boxes because of the lack of working space inside these devices. The inside working area of many such traditional excavating machines having trench shoring features are overly cluttered with structures and other machinery, which deprives the workers of a suitable amount of area within the trench box for performing their work.
Accordingly, there is a need to provide a trench box that is capable of moving itself within the trench. There is also a need to provide such a self-movable trench box without including excessive equipment and structures inside the trench box area so that there remains sufficient room for workers to move about within the trench box. There is a further need to develop a self-propelled trench box which will clear and grade the bottom surface of the trench so that the trench box can move back and forth within the trench without being obstructed by broken or loose material that has fallen from the sidewalls of the trench.